Found a Westy!

[Komet]

Thanks Tom, today I have checked several voltages.

On the Horizontal Output tube, my schematic report this value

Cathode: 3.5V
G1: -20V
G2: 130V

And on my set I have

Cathode: 5,43V
G1: -17
G2: 165

Agreed with the law of ohm, and my 57ohm cathode resistor, the cathode current is 95mA. Good.

The strange situation is on the damper circuit. On the schematic I have 560V on cathode and 320 on anode. But I have over 1000V on cathode and on the anode... I burned my multimeter

[Komet]

After the death of my chinese-import digital multimeter, I used an old ICE analogic multimeter and I measure 400V on the cathode of damper. Low, but good for now. Tomorrow I try with another multimeter, for better control

http://imageshack.us/photo/my-images/829/westhor.jpg/

http://imageshack.us/photo/my-images/338/dsc05004v.jpg/

And now, time to LOL. The CRT was rebuilt in Italy, and the label on the neck says "without ion trap". But...

http://imageshack.us/photo/my-images/339/dsc05000a.jpg/

[enrico6v6]

I also have a nib/nos rebuild tube to be used without ion trap, it's a 90° 17" . Ion trap in this westy appears to be fitted in a position that does not affect the gun. This could be done for don't miss it ...

[Giulio Maiocco]

Hi Komet, how are you?

Don't try to measure the voltage on the damper's plate, with this kind of circuit, there is a pulsed waveform on 6W4's pin 5 that easily exceed 1Kv at radio frequency, so no wonder you fried your meter! Also, your misshap with the Fivre 6W4 is quite expected, H-K insulation on this tube is rated only 450VDC and this tube is quite fragile per-se. If you want to stay "relaxed", you can always use a 6AX4 damper, a MUCH better tube all around

Cheers

Giulio

[Komet]

Hi Giulio

I'm fine thanks

I know that in many circuits I cannot measure the plate of damper tube, but if you look at the schematic that point is marked with a known voltage. It seemed strange, and I thought of a error. In many set for checking the EHT you must see if the booster tension is similar at the value reported in the schematic (like my Blaupunkt CTV200).

Enrico tell me about the 6W4 and I had thought to keep the 6AX4 as you say, since this tube has a better insulation of the heater

Thank you

Marco

@Enrico: in fact the screen has a good light when it's on, if the ion trap have an effect on the gun I would have problems

[Giulio Maiocco]

Hi Marco, nice to know the "real" name of the person behind the nickname!

Measuring the plate voltage at the damper is *generally* safe if the flyback is of the autotransformer variety (almost all of the italian ones, btw), but the one in your westinghouse and a very similar one employed on some early Radiomarelli sets is a true transformer with separate primary and secondary windings. When you want to measure a voltage that has past thru a flyback winding, in this case the plate voltage on the damper tube, do it with a high voltage probe, as it's almost guaranteed that there are high voltage pulses that will fry your "normal" DMM.

I know flyback transformers construction quite well, I built some from scratch and they perform surprisingly well.

About the 6AX4, yes, it's a better tube, but if you are a purist and want to retain the original 6W4 (IMHO, not recommended!), please float the filament with respect to ground, maybe adding a small separate filament winding, but be warned, it must have a good insulation! There is no reason risking the flyback transformer if (when) another 6W4's insulation fail

Cheers

Giulio

[Komet]

Hi Giulio; I have a Marelli RV109, look here. I have yet to fix it.

http://videokarma.org/showthread.php...ighlight=RV109

I'm not a purist in the strict sense of the word, a restoration is always a compromise and if an intervention does not ruin the TV as changing a tube makes its use more secure is acceptable. It is better than change the circuit with an external transformer.

However, today I turned on the set for the first time after the failure of 6W4 for 5-7 minutes. The flyback was barely warm, nothing to worry about. The volume-contrast double potentiometer is damaged in the contrast section, I hope to save it. I cleaned some other potentiometers, tomorrow I connect a test pattern and cross my fingers.

[47'Plymouth]

hey use a Variac...between the set and the power outlet for excellent protection of your internal parts it protects your house wiring too
from fire

[Dan Starnes]

I have a 1959 Westy floor model that is one of my best performers. Very cool.

[Giulio Maiocco]

Hi again Marco,

Sorry to hijack this thread, I know quite well the RV109 chassis, as I restored more than a few of these, the 21" CRT variant to boot! Be wary of the awful paper capacitors and sometimes mica ones could cause problems in the horizontal section. Another weak point of this chassis is the cup holding the 1B3 socket, it tends to accumulate lots of dust and dirt, helping the EHT discharge with a loud snap.

About the similarities of the flyback used on your Westinghouse, I was referring to the older Marelli, like the RV90, RV94 and similar Tv sets

Cheers

Giulio

[Komet]

My Marelli has no vertical deflection, almost certainly needs recapping, and have a loss of insulation from the EHT cable. It needs a lot of work...

Back to Westy, tomorrow I rebuilding one electrolytic capacitor on the vertical deflection. The picture is just bigger than normal because the EHT voltage is a little bit low, but for now is ok. Probably needs an IF audio realignment, and the contrast potentiometer doesn't work very well.

[Komet]

Vertical problem solved







Next mission: low power audio, disturbed, I tried retune FI audio but nothing changes. 6V6 and 6AU6s are good. Maybe it connected at no snow effect on video without signal, low RF amplification...

[Electronic M]

If you vave no noise on the screen (blank raster) regardless of whether or not there is a signal, the audio is weak and or distorted, and the audio is taken off past the video detector diode in the signal chain, then your video detector diode may be bad. I had this happen on a 1953 Zenith once. It used a germainium diode and it had gone bad causing symptoms similar to what you describe.
Just a possibility to save you the head scratching/banging it took me to find that in problem my Zenith.

[Komet]

Thanks for the info, i will try another germanium diode like OA91

[Komet]

I tried to change the diode, no results. The voltage on the anode and on G2 of the 6V6 are normal. I will try to connect my MP3 to the volume control and see what happens, if it sounds good I will check the voltages of the 6CB6 and I will try to replace the 6AK5 (RF amplifier).